Chips in Space: Let’s look inside ARISSat-1 (Part 3)

The third and final chapter on the ARISSat-1's subsystems, which covers all of the Cs: communications, cameras, control and cabling, along with the university experiment that hitched a ride.

Welcome to my third and final chapter on the ARISSat-1’s subsystems, which covers all of the Cs: communications, cameras, control and cabling, along with the university experiment that hitched a ride. Next week’s blog post will begin a discussion of the challenges we encountered while designing the satellite—and how we solved them—followed in later posts by a summary of the lessons learned from ARISSat-1’s deployment and operation.

ARISSat-1 has been in operation for three weeks, now. The most up-to-date status information can be read at http://www.arissat1.org/v3/ and the AMSAT Bulletin Board. The battery is surely dead. ARISSat-1 orbits the Earth every 90 minutes. On each orbit, when it enters eclipse, no power is generated by the solar panels and the systems effectively reset. Otherwise, operations continue to be nominal.

Let’s finish up the description of the subsystems…

Interior View of the Receiver RF PCB

RFThe RF module has a 2-meter-band communications transmitter for the downlink, and produces a total of 500 milliwatts of power. The input to the downlink transmitter is a 10.7 MHz intermediate frequency (IF) signal that is generated by the Software Defined Transponder (SDX). (See Part 1 for more info on the SDX.) The RF module also has a 70-centimeter-band communications receiver, and its output is a 10.7 MHz IF signal that is fed to the SDX.

Concept Drawing Showing the 2-meter Antenna at Top and 70-cm Antenna at Bottom

AntennasThere are two antennas. The 2-meter downlink antenna is mounted to the top, and the 70-cm uplink antenna is mounted to the bottom. As mentioned in my deployment update blog of August 3, 2011, the 70-cm antenna appears to be broken off in the video of the deployment. We may never know what happened to that antenna, but to our pleasant surprise, radio amateurs are still able to communicate with ARISSat-1 just fine using 1 Watt on the uplink.

Interior view of the camera module

CamerasWe used Hunt Electronics’ HTC-2N3 Series CCD Sensor type cameras. There are four cameras, each pointing in a different axis. If you take a look at the ARISS SSTV Gallery site, note that the call sign RS01S is in four different colors:

The output is NTSC video that is digitized by the four-channel video input processor on the Internal Housekeeping Unit (IHU), which was also discussed in Part 1.

Exterior view of control panel

Control panelThe control panel allowed the cosmonauts to activate the satellite. It is an important component of the safety system. Upon flipping the three toggle switches, power was applied to the satellite and the safety timers were enabled, giving the cosmonauts 16 minutes to safely deploy the satellite before it started transmitting.

One of the First Pictures ARISSat-1 Took (captured by Mike Rupprecht, DK3WN)

Once ARISSat-1 was powered up, it started taking pictures. Two of the photos captured the cosmonauts handling the satellite. Here’s one that was captured by Mike Rupprecht, DK3WN, of Germany.

Photo of the Kursk University experiment

Kursk experimentTo the right of the control panel on the top plate is the Kursk science experiment. This experiment was developed by students at the Kursk State University in Russia, and is intended to measure the vacuum of space. The experiment was started 30 minutes after deployment, and will run once each day for a complete orbit. Telemetry from the experiment is transmitted on the downlink.

Interior View of ARISSat-1 Showing the Cabling

CablingNo satellite is complete without cabling. Cables are something that you wish to minimize because they are not easy to assemble, are very labor intensive and take a long time to assemble. They are also prone to vibration failures, if not carefully laced with connectors secured in place. The cable harness was handmade. Individual strands of insulated wire and connectors were assembled according to the length of the cable run and the placement of the connectors. This makes for a nice, neat installation. It also facilitates the cable-harness tie downs, which keep the cable harness in place.

That’s a wrapThere you have it, each and every subsystem of ARISSat-1. Please check out the below links for more background info and the latest news on this project. And, please post comments about what you’d like me to cover in future posts, as well as any questions I can answer for you.

Hi again Steve, Thanks for the excellent 3 part article, I have saved mine to disc for future reference but just wanted to say thanks for the great effort you and the team went too to create and launch the satellite, I hope she continues to give many people lots of enjoyment and the interesting data goes into the next project to help many more satellites big and small come through to future flights too. Just wish ITAR would ease up on all our AMSAT satellites and us all working together again as one International team. Best regards from us all over here, Chris GW6KZZ.

Hi R.D., Thanks! We followed good engineering practices. Soldering was all by hand under a stereo microscope paying particular attention to make good solder joints. Components are industrial grade. The only component space rated was the solar panels. No paints or glues that out-gassed.
I do plan a lessons learned blog or two or three. Stay tuned!

Thanks for a nice series of articles! I was wondering what if any special fabrication methods were used to accommodate the space environment? In particular, type of soldering used for the PCBs, type of components (industrial, commercial, or de-rated use of these?). Would you be posting a lessons learned article as some point in the future?

I was giving an update from previous blog posts. In summary, the battery was given to us. It is the same one used in the Russian Orlan space suit. The chemistry was Silver-Zinc, which was designed for high reliability - naturally for the suit - and not for longevity. We thought if we shallow charged it, it would last longer. Alas, it only lasted 8 days. So for the rest of ARISSat-1's operating lifetime, it will only operate in the Sun. I hope this helps explain the update and the battery choice. We will be thinking about alternative battery choices in the future. But we did learn from this mission.

I was curious as to why you said the battery was dead and when the solar panels are eclipsed, the system resets. Why were rechargeable batteries or ultracaps not used to hold the system over? Added caps? The interrupted time was just not important? Just curious about that design choice :)